"circa"= about "dia"=day

almost everything in you boday has it.

Physiology- 1) hormones 2) body temp 3) gene expression

Behaviors- 1) sleep 2) cognition

you spend 1/3 of your asleep

Orginally thought of as a:

Passive state of immobility with cessation of brain activity

lack of perception and consciouness

Now we know:

-sleep is composed of different states of brain actibity

-some perception- wake up faster in response to your own name than the names of other.

1) Electroencephalogram (EEG) - records "brainwaves"- sum of electrical activity over an are of cortex

2) Electrooculogram(EOG)- records eye movement during sleep

3) Electromygram (EMG)- detects activity in neck muscles during sleep

Awake and alert: Beta brain waves

Awake but Drowsy: Alpha brain waves

Stage 1 NREM Sleep: Mixture of alpha adn theta brain waves

Stage 2 NREM sleep: Sleep spindles, K complexes, theta brain waves and begginnings of delta waves

Stage 3 NREM Sleep: Mixture of theta and delta brain waves

Stage 4 NREM Sleep: Delta brain waves

REM Sleep: Fast, active brain waves accompanied by rapid eye movements (REMS)

Delta or slow-wave sleep (SWS) sleep is mostly observed at the begginning at the night and REM sleep is mostly observed at the end of the night (last 2-3 cycles)

Stages 1&2 =light sleep

stages 3&4 "deep" slow wave sleep

Why do we sleep?

1) recuperation theory

2) circadian theory

3) memory/ performance theory

1) restore homeostassis: restore the physiological processes that have been altered during wakefulness

2) adaptive response: conserve energy by reducing the metabolic rate and lowerin body temp.protect organism form mishap and predators at night

3) cognitive function: consolidate information from the day prior/optimize performance

Certain sleep stages improve certain memories selectively

Stickgold& walker 2004

Mednick et al 2009

Stickgold &walker 2004

-Stage 2- procedural memory

-sws-declarative, spatial memory

Mednick et al 2009

-REM- emotional memory,creativiy

1) Insomnia- inablity to fall or stay asleep

2) Narcolepsy- "sleep attacks" subjects enter diretly in REMs, Cataplexy-loss of muscle tone while awake, triggered by intense emotion or food

3) sleep Apnea- Stop breathing during the night, leads to repeated awakenings, most commonly seen in males, the overweight, and the elderly

Sleepwalking,talking, and night terrors occur mostly slow-wave sleep.

When awakened in REM, most likey dreaming.

Dreams are hard to study ...

Most dreams occur in REM, but dreams occur during both REM and NREM Sleep

-REM dreams

*more vivid dreams

*able to incorporate external stimuli

-NREM dreams

*more vague, less imagery, less emotinal

*rarely remembered

The body will make up for lost REM, so does it serve a function?

REM sleep may help cope with emotions...

-increased stress=increased REM

-Increased REM=better memory for emotional stimuli

-individuals with REM sleep are able to dissociate emotion from memory- copin with emotional memories.